Personality can be defined in terms of enduring individual differences in emotional, interpersonal, experiential, and motivational styles. The five factors of Neuroticism, Extraversion, Openness to Experience, Agreeableness, and Conscientiousness provide a comprehensive taxonomy of personality traits for the description of personality in aging men and women. Two studies were conducted as part of continuing program of research on these factors. In the first, alternative measures of the five- factors were compared, and both general agreement and specific differences were found. In the second, items of the California Q-Set were used to examine the discriminant validity of facets of each of the five factors.